Infiltration Heat Loss Calculation UK

Infiltration Heat Loss Formula:

\[ Q = ACH \times Volume \times \Delta T \times 0.33 \]

Infiltration Heat Loss (Q):

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1. What is Infiltration Heat Loss?

Infiltration heat loss refers to the energy lost when outdoor air enters a building through cracks, openings, and unintentional ventilation, requiring additional heating to maintain comfortable indoor temperatures.

2. How Does the Calculator Work?

The calculator uses the infiltration heat loss formula:

\[ Q = ACH \times Volume \times \Delta T \times 0.33 \]

Where:

\( Q \) — Infiltration heat loss (W)
\( ACH \) — Air changes per hour (air changes/hr)
\( Volume \) — Room or building volume (m³)
\( \Delta T \) — Temperature difference between inside and outside (°C)
\( 0.33 \) — Specific heat capacity of air (Wh/m³°C)

Explanation: The formula calculates the heat energy required to warm the infiltrating outdoor air to indoor temperature levels.

3. Importance of Infiltration Heat Loss Calculation

Details: Accurate infiltration heat loss calculation is crucial for proper HVAC system sizing, energy efficiency assessments, building insulation design, and compliance with UK building regulations.

4. Using the Calculator

Tips: Enter ACH based on building tightness (typically 0.1-2.0 for UK buildings), volume in cubic meters, and temperature difference in °C. All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What are typical ACH values for UK buildings?
A: Modern well-sealed buildings: 0.1-0.5 ACH; Average older buildings: 0.5-1.5 ACH; Poorly sealed buildings: 1.5-2.0+ ACH.

Q2: How do I measure building volume?
A: Calculate volume by multiplying floor area by ceiling height. For irregular spaces, break down into regular shapes and sum the volumes.

Q3: What temperature difference should I use?
A: Use design temperature difference based on local climate data, typically 20-25°C for UK winter conditions (indoor 20°C, outdoor -3 to 0°C).

Q4: Why is 0.33 used in the formula?
A: 0.33 represents the volumetric specific heat capacity of air (approximately 0.33 Wh/m³°C), accounting for the energy needed to heat 1 m³ of air by 1°C.

Q5: How can I reduce infiltration heat loss?
A: Improve building sealing, install weather stripping, use draught excluders, upgrade windows and doors, and ensure proper insulation throughout the building envelope.